1. Field of the Invention
The present invention relates to an inkjet recording apparatus and an inkjet recording method, and more particularly, to an inkjet recording apparatus and an inkjet recording method which are able to suppress the occurrence of local offset after fixing by a heat roller.
2. Description of the Related Art
An inkjet recording apparatus is an apparatus which forms an image by continuously ejecting droplets of ink onto a recording medium, and since this kind of apparatus is able to record images of high quality by means of a simple composition, it is widely used both as a domestic printer for individual use and as an office printer for commercial use. In the case of office printers for commercial use, in particular, there are increasing demands for higher processing speed and higher image quality.
In an inkjet recording apparatus, if ink is made to undergo an aggregating reaction and the image is fixed by a heat roller in a state of containing a large amount of water, then there is a problem of offset of the image. In particular, if a large dot is formed and then a further large dot is superimposed on the portion where this large dot is formed, then the image (dot) height becomes relatively high and local offset occurs. In particular, in a recording method in which wetting and spreading of dots is suppressed by an aggregating reaction and high-speed printing is carried out by a one-pass recording method, the drying time is limited and this offset is especially marked.
Japanese Patent Application Publication No. 2008-100511 discloses an inkjet recording method in which an image is formed on a coated paper having a specified pure water transfer amount on the basis of a blister method, and after becoming touch dry, the image is fixed by a heating roller. In the method described in Japanese Patent Application Publication No. 2008-100511, since an image is formed on a coated paper having low permeability, then an image of high quality cannot be obtained. Furthermore, since this system is a non-aggregating system, then incorporation of water into the image is not liable to occur and the system is essentially beneficial in respect of offset. Therefore, the issue of local offset occurring when an aggregating reaction is applied to image formation onto a coated paper has not been recognized.
Furthermore, Japanese Patent Application Publication No. 2008-62503 describes an inkjet recording method and a recording apparatus which deposit a treatment liquid having a function of aggregating ink onto a coated paper. According to the image forming method and image forming apparatus described in Japanese Patent Application Publication No. 2006-82254, a head is disclosed in which drive waveform including drive signals for ejected droplet volumes Mj of Mj0, Mj1 and Mj2 (Mj0>Mj1>Mj2) is developed and output, and ejected droplet volumes of different sizes can be ejected. However, when performing two-way printing, the landing sequence of the liquid droplets is different in the outward printing action and the return printing action, and hence there is the decline in image quality, such as the occurrence of color differences, divergence of the color hues, and marked banding in the image.
However, Japanese Patent Application Publication No. 2008-62503 and Japanese Patent Application Publication No. 2006-82254 do not provide research into local offset occurring when an aggregating reaction is used in forming images onto coated paper.